The Role of Host Genetics, Intestinal Microbiota and Metabolome as a New Insight into IBD Pathogenesis

Inflammatory bowel disease (IBD) is an incurable, chronic disorder of the gastrointestinal tract, whose incidence increases every year. Scientific research is constantly delivering new information about the disease and its multivariate, complex etiology. Nevertheless, full discovery and understanding of the complete mechanism of IBD pathogenesis still pose a significant challenge to todays science. Recent studies unanimously confirmed the association of gut microbial dysbiosis with IBD, as well as its contribution to the regulation of the inflammatory process. It transpires that not only the altered composition of pathogenic and commensal bacteria is characteristic of disturbed intestinal homeostasis in IBD, but also of viruses, parasites, and fungi, which are active in the intestine. In fact, the crucial function of microbial metabolome in the human body is altered, which causes a wide range of effects in the host, thus providing a basis for the disease. On the other hand, human genomic and functional research revealed more loci that play an essential role in gut homeostasis regulation, immune response, and intestinal epithelial function. This review aims to organize and summarize currently available knowledge concerning the role and interaction of crucial factors associated with IBD pathogenesis, particularly host genetic composition, intestinal microbiota, and metabolome, with immune regulation.